Well, I hate to say it, but no matter how much you work out, if you lose a significant amount of weight from your high weight, you're going to have some sag. There is just no way around it.
However, I don't think it will be as bad as you fear. The slower you lose, the way you lose, and whether or not you are eating healthy (not crash dieting over and over again) and exercising makes a difference in
how much. But here's what you need to know even more -- it doesn't matter. If you have a bit of flab on your tummy or on your arms, it won't matter. Because for the most part, what people will see is you with your clothes on. So, from your pic, you look pretty young. I'd say if you lose weight slowly and steadily, work out, and do all the right things, sag will be there, but not horrid. Another way to tell is if anyone in your family has done something similar. You will be able to tell from their skin. But for me, I no longer care about saggy skin. I just want to be healthy, feel better, AND look as good as I can! Cause that skin all puffed out with fat can't look too good! Good luck and hope this wasn't a downer!